High-temperature heat capacity and thermodynamic properties for end-member titanite (CaTiSiO5)

 The heat capacity of end-member titanite and (CaTiSiO₅) glass has been measured in the range 328–938 K using differential scanning calorimetry. The data show a weak λ-shaped anomaly at 483 ± 5 K, presumably associated with the well-known low-pressure P2₁/a ⇆ A2/a transition, in good agreement with previous studies. A value of 0.196 ± 0.007 kJ mol⁻¹ for the enthalpy of the P2₁/a ⇆ A2/a transition was determined by integration of the area under the curve for a temperature interval of 438–528 K, bracketing the anomaly. The heat capacity data for end-member titanite and (CaTiSiO₅) glass can be reproduced within <1% using the derived empirical equations (temperature in K, pressure in bars):

Multifractal and entropic properties of landslides in Japan

Landslide distributions in two major areas of northern Japan, Tohoku and Hokkaido, are analysed for multifractal properties. For the latter data set, also the multifractal spectrum for the spatial landslide size distribution is determined and compared to the probability distribution. It is concluded that the fields possess definite multifractal character. This finding is supported by the known multifractality of the main triggering processes, rain and earthquakes. Further support comes from a configuration entropy analysis which is found to be a useful complimentary tool to multifractal analysis. Models leading to multifractality are briefly reviewed. Careful attention is paid to the algorithms used and to the verification of the numerical results. Some general suggestions concerning numerical methods are made.     

前震活动特征及其识别的研究（Ⅰ）

分析了近２０年来中国大陆强震（Ｍ≥７．０）和华北地区中强地震前广义前震序列时间和空间分布的多分形特征，计算其广义分维谱Ｄｑ和标度指数谱Ｆ（α），并探讨了它们随时间的变化．结果表明：（１）对广义前震活动，在所研究地区的时、空分布，均呈现多分形结构；（２）大地震发生前半年至一年，地震活动时、空分布的高次分维Ｄ∞呈下降趋势．这种降维特征，亦在实验室含水大样本岩石破坏前，声发射序列Ｄ∞的变化中观测到；（３）与中强地震相比，大地震孕育区地震活动的空间高次分维偏低，表明地壳应力分布的高度不均匀性，是板内大地震孕育环境中的本质因素之一．     

Multifractal measures of earthquakes in west Taiwan

The generalized fractal dimension for epicentral distribution of earthquakes in west Taiwan is measured. The entire area is first divided into two zones, i.e., north and south zones, after which the two zones are further separated into three subzones for the former and two for the latter. The logC _q (r) versus logr function, whereC _q (r) is the generalized correlation integral andr is the distance between two epicenters, shows that a linear relation between logC _q and logr exists in the range ofr smaller thanr _c . The value ofr _c is 25 km for the north zone, 40 km for the south and 12 km for the three north subzones. The valuesr _c =25 and 40 km are almost the smallest ones of the width of epicentral distributions of the north and south zones, respectively. The value ofr _c =12 km for the three north subzones is approximately the smallest size of the cluster of epicenters. For the plots of two south subzones, the pattern of data points does not bend in the range ofr in consideration, and, thus, there is not such a critical radius. TheD _q –q relations forq=0, 1, 2,..., 15 are constructed for the two zones and five subzones. Results show significant multifractality and a spatial variation in multifractality for epicentral distributions of earthquakes in west Taiwan.     

地球物理信号能量(密度)多维分形及应用

地球物理信号代表的地质地球物理过程在多种尺度上和尺度之间表现为自相似性（self-affinity)或尺度无关性（Scale Invariant)，称为地球物理信号的分形性质，多个分形地球物理信号叠加在一起表现为多维分形特征，研究多维分形地球物理信号的能量或能量密度特征，可以进行时间或空间地球物理信号的校正、奇异性研究分析，或进行不同地球物理动力学过程的分解，本文描述了地球物理时间（空间）信号的多维分形过程和功率谱密度（能量密度）与波数以及重磁场能谱密度及面积（能量）与能谱密度的多维分形关系，并用地球物理测井与重磁资料作了试算。     

空间自相似性与地球物理和地球化学场的分解方法

场的分解是应用勘查地球物理和地球化学数据所必不可少的数理处理工作，这项工作往往是为了分解不同的场来研究和了解不同的地质以及相应的地质过程，比如划分不同岩石类型以及识别和圈定矿化蚀变睡.闰定地质过程所产生的同类型的地质体并不简单地对应于相同的场值和频率，场的分布特征往往还与地质体的几何形态，。埋藏深度以及与其周围地质体的相对差异有关。然而，由于地质过程往往具有多期次和空间相关性等特点，所产生的地质体或者相应的场往往会呈现空间自相似性或统计自相似性。这种自相似性可以帮助分解不同地质过程所产生的同类地质体，文中所介绍的多重分形（multifractal)滤波方法（S－A）根据场的能谱分布的不同空间自相似性形成不规则甚至分形滤波器，并将场分解为不同同的组份，如局部异常和背景场，应用该方法对多处地球化学和地球物理场的处理结果表明，该方法对区分与矿有关的局部异常与背景场是很有效的，对加拿大NOVA SCOTIA省西南部航空放射性铀钍钾（U-Tn-K)数据处理所分解的异常对反映岩体中与铀－钨－锡（U－W－Sn)矿化有关的围岩饰变具有明显的效果。     

Precursors Revealed by the Multifractal Dimension Around Ordos Block,North China

Seismicity around the Ordos Block in the northern part of China has been studied by the multifractal dimensions with the help of complete data set of earthquakes with M≥2.5 since 1977.Seven regions around this block have been examined whiere the eight large earthquakes with M≥6.0 for the complete data occurred.In oirder to display the temporal distribution of the correlation dimension D2,a moving window of fixed number of events is used in every of the seven regions.Except for two regions with less seismic activity,all other five regions have obviously been found to display sudden changes of the correlation dimension for the events with M≥4.5.     

APPLICATION OF MEM SPECTRAL ESTIMATION TO MU RADAR OBSERVATION

Preliminary results of the wind velocity estimation using the Maximum Entropy Method (MEM) to MUradar observation data sets are presented. The comparison of the results from the periodogram method and theMEM shows that the MEM estimation is reliable, and has higher accuracy, resolution and detectability than theestimation from periodogram method. The high accuracy power spectrum obtained by the MEM is veryuseful to studying the atmospheric turbulence structure. However. the MEM needs the longer computingtime for obtaining the high accuracy spectrum. Particularly, the estimation of MEM will bring serious devia-tion at lower signal-to-noise ratio.     

从美国地球物理学会2001秋季年会谈非线性地球物理进展

简要介绍美国地球物理协会2001秋季年会“非线性地球物理”分会的活动情况。它可以大致反映出目前非线性理论和非线性地球物理的发展现状和趋势,尤其是在分形,多维分形,尺度独立性,混沌和自组织临界理论方面的研究。     

超谱遥感图像快速聚类无损压缩算法

K-means聚类要求每个像素要和所有聚类中心求欧氏距离，当聚类数很多时，这是一个相当耗时的工作。改进的K—meam聚类算法根据历史聚类结果进行初始类分割，即节约初始聚类时间，又能使历史聚类过程中形成的类间稳定关系得以保持；类内像素只和相邻的聚类中心计算距离进行聚类，随着算法的迭代进行，大量类的状态基本固定，使得聚类速度不断加快。基于改进K-means聚类的无损压缩算法具有充分利用历史聚类成果和收敛速度快的特点，通过提高类内像素冗余度，最大限度消除谱间冗余和空间冗余。采用多次聚类压缩的结果预测最佳聚类数的方法，可实现最小熵无损压缩。通过和DPCM算法概率模型的熵值比较及实验数据的分析，验证了基于聚类无损压缩效率比不聚类无损压缩效果更优。